The present invention relates to the alignment of optical elements, and more specifically to the alignment of optical elements using a laser beam and a diffractive optic to form a projected reticle image, wherein the optical element is aligned in response to a reflected reticle image displayed upon a screen.
Many telescopes rely upon a mirror or a mirror system to capture and reflect a desired image. However, for telescopes to operate properly, the mirrors must be properly aligned. The alignment of the mirrors in a telescope can be a very cumbersome and time consuming process. Many different methods have been utilized to align the mirrors so that a primary mirror would be aligned with a secondary mirror. For example, a prior method requires use of a specialized eye piece with crosshairs and apertures to align the telescope. In order to use these optical alignment devices, the large primary mirror must be removed. The center of the primary mirror is then located and a black dot is placed in the center of the mirror. Such removal of the mirror subjects the primary mirror to potential damage, such as scratching or breakage.
An alternative method of aligning the optical elements in a telescope is to use a known star and align the telescope in total darkness. However, this method wastes valuable observation time. Further, the accuracy of the alignment is limited to the image of the star, and the image of the star is substantially degraded by passage of the light through the atmosphere.
Newtonian type telescopes are subject to misalignment of the optical elements by shifting due to repositioning of the telescope or by transporting the telescope. A misaligned Newtonian telescope will exhibit an image of a star that looks like a comet with a tail. The misaligned telescope is not efficient in the collection of light as a light bundle is not centered on the mirror.
Lasers have been used for several years for aligning the mirrors in a telescope. In a properly aligned or collimated telescope, a laser beam is projected through an emission aperture to reflect off the secondary mirror which directs it to the center of the primary mirror. The primary mirror reflects the beam back to the secondary mirror which then reflects it back to the emission aperture of the laser. The complete return of the laser through the emission aperture assures that the telescope is correctly aligned. However, in order to accurately use a laser in aligning a telescope, the telescope must be modified for the use of a laser. The primary mirror is removed and marked with a small white circle circumscribing the center of the mirror. The white circle provides a sighting target in the alignment process to confirm that the laser beam is placed in the center of the mirror. The laser is then aligned with the white circle. Once again, the disruption of the telescope is required and subjects the mirror to possible harm.
Some telescope designs employ a cored primary mirror. A cored primary mirror includes a hole in the center of the mirror. This hole precludes any of the previous alignment methods that rely upon dots, circles or markings at the center of the primary mirror. A telescope having a cored primary mirror must be aligned by the stars, and thus suffers from the accompanying problems.
Therefore, a need exists for aligning optical elements wherein the optical elements can remain in place during the alignment operation. A further need exists for the alignment of optical elements wherein a reflected reticle image from the optical elements is displayed and the alignment can be made in response to the displayed image.
The need also exists for the alignment of optical elements in a telescope without requiring extensive downtime of the telescope. A further need exists for the alignment of the optical elements in a telescope without exposing the optical elements to potential damage, such as scratches or breakage. A still further need exists for aligning the optical elements in a telescope in a simple, inexpensive manner in which most people can perform in a relatively short period of time.
The present invention provides for the alignment of optical elements in response to the projection of a reticle image and a display of a reflected reticle image upon a screen. Thus, a reflected reticle image is displayed upon a viewing screen and the optical elements are aligned in response to the displayed reflected image on the viewing screen.
In one configuration of the system, a reticle image generator is optically intermediate a display screen and the optical elements to be aligned. An application of this configuration for a telescope locates the reticle image generator in an eyepiece tube. The display screen is proximal to the operator. The generated reticle image is projected upon the optical elements and a reflected reticle image intersects the display screen for viewing by the operator.
In alternative constructions, the reflected reticle image may be electronically captured and formed on a display screen. Thus, the display screen may be electrically powered such as a CRT, LED or LCD.
The present method contemplates creating a reticle image, projecting the reticle image on the optics to be aligned, forming a reflection of the reticle image from the optics, displaying the reflected reticle image on a display and aligning the optics in response to the reflected displayed image.